Not Applicable
1. Field of the Invention
This invention relates to cardio myopathy and the treatment thereof.
2. Description of the Prior Art
By way of background, cardio myopathy, as caused for example by myocardial infarction, is a common disorder. Twenty thousand new cases are reported yearly in the United States and 25-50% of such cases will result in death after three years. The problem is that damaged adult heart muscle does not regenerate and myocardial functionality cannot be restored using the body""s natural healing mechanisms. The myocardium tends to dilate and areas of the ventricular walls may become hypokinetic, or even akinetic, such that congestive heart failure often develops in affected individuals.
Previous medical techniques have not substantially reduced the morbidity or mortality of this condition. Past efforts in this area include removing autologous muscle cells, stem cells, etc., and culturing them to generate the large number of implantation cells necessary for myocardial repair. The cultured cells are then implanted via injection into the myocardium, where they have an opportunity to regenerate new heart muscle. Applicant has previously proposed a cell patch method whereby autologous muscle grafts are applied to damaged myocardial tissue. See U.S. Pat. No. 5,327,913. According to this method, the muscle grafts are placed against a patient""s outer myocardial wall and a section of the patient""s greater omentum is applied over the grafts to supply blood to the transplanted tissue. In a recently developed improvement of the cell patch method, a percutaneous procedure is used to secure the muscle grafts to the myocardium. Applicant has also recently proposed a micro-granule treatment wherein autologous myocyte micro-granules are injected into a patient""s inner or outer myocardial wall using an injection needle introduced via a transfemoral or surgical approach. According to a further recent proposal by Applicant, a cradle-assisted myocardial repair and treatment method uses a cradle designed for engagement with the myocardium and injection of a myocyte donor material therein. In one cradle embodiment, the cradle is introduced via a transarterial-endocardial approach and is inflated within a ventricle to engage the endocardial wall. In another cradle embodiment, the cradle is introduced percutaneously via an epicardial approach and is adapted to wrap around a portion of the outer myocardial wall. In each of the foregoing cradle embodiments, the cradle supports injection needles for injecting a desired material into the myocardium.
Evaluation of the various treatment proposals outlined above suggests a need for a more efficient method of applying myocyte donor (or other) material to the myocardium. For example, transcavitary myocardial injection of material requires arterial puncture and a needle carrier to deliver cells or drugs into the myocardium. In addition, X-ray imaging has to be available to guide the needle into the proper position. The cradle assisted myocardial repair proposal described above makes use of a percutaneous approach in one of its embodiments and thus has many advantages over transcavitary procedures. However, the cradle-assisted proposal may not be optimal for all myocardial repair and treatment scenarios and applicant believes that further improvements in myocardial repair and treatment may therefore be realized.
The foregoing problems are solved and an advance in the art is obtained by a novel apparatus for percutaneous epicardial injection. The injection apparatus includes a catheter having a tubular wall, an interior portion surrounded by the tubular wall, a base end, a distal end, and a central longitudinal axis extending between the catheter base end and the catheter distal end. The catheter distal end has an end face oriented at an oblique angle relative to the catheter longitudinal axis and is adapted to attach to a myocardium using suction. A lumen extends from the catheter base end to the catheter distal end within the catheter interior. The lumen is adapted to slidably support an elongated syringe having a needle tip adapted for movement between a retracted position wherein the needle tip is recessed within the catheter interior to an extended position wherein the needle tip extends from the catheter interior. The injection apparatus may be used to introduce a myocardial repair or treatment material into a dysfunctional area of the myocardium while the catheter distal end is attached thereto by extending the needle tip into the myocardium and injecting the myocardial repair or treatment material into the dysfunctional area.
The catheter distal end is provided with suction elements that are adapted to facilitate the aforementioned suction attachment of the catheter to the myocardium. The suction elements may include a plurality of openings located in spaced relation around the tubular wall end face. In a modified construction, a soft tubular ring member is mounted at the catheter distal end. The ring member has a plurality of openings located in spaced relation around an exposed face of the tube that provide the suction elements. In either construction, the suction elements can be respectively connected to plural corresponding vacuum passages that extend in the tubular wall from the catheter distal end to the catheter base end. Alternatively, the suction elements can be connected to a single vacuum passage that extends to the catheter base end.
The percutaneous epicardial injection apparatus of the invention may further include a second lumen extending from the catheter base end to the catheter distal end within the catheter interior, and carrying an optical imaging device and light source. A third lumen may likewise be provided for carrying an ultrasound probe. In a further alternative implementation of the invention, a cell counter can be mounted on the tubular wall for monitoring repair cell introduction into the myocardium. A pair of electrodes can also be mounted at the catheter distal end for EKG monitoring or the like.
The catheter interior can be either hollow or solid filled. If the catheter interior is hollow, the catheter will preferably include a cover member mounted on the tubular wall at the catheter distal end. The cover member is perforated to receive the various lumena. If the catheter interior is solid filled, it will be perforated with passages extending between the catheter distal end and the catheter base end to provide the lumena, or to receive separate tubes that provide the lumena.
In addition to the above-summarized percutaneous epicardial injection apparatus, the invention further contemplates a procedure for applying a myocardial repair or treatment material to a patient""s myocardium. This procedure is initiated by inserting via percutaneous approach beneath the xiphoid bone of a patient, a small needle into the patient""s pericardium. A guide wire and balloon dilator are then introduced into the patient""s pericardial sac and the pericardial sac is dilated. Following elevation of the patient""s heart (as necessary), the medical practitioner selects the percutaneous epicardial injection apparatus of the invention and prepares it for use. The catheter is introduced into the patient using the previously formed sub-xiphoidal opening and guided into the pericardial sac. Advantageously, the catheter can be self-guided to the selected area without X-ray imaging using the optical imaging system summarized above. Moreover, the above-summarized ultrasound imaging device can be used to appraise ventricular motility. When the selected area is identified, the catheter distal end is attached to the myocardium with the aid of its oblique tubular wall end face and associated suction elements. The needle tip of the syringe may now be extended into the selected area and the repair or treatment material may be injected into the myocardium.